rcd tripping

[PeterMount]

My customer's RCD trips on the CU, but only when the induction hob CB is on, and never when the induction hob itself is switched on and operational.
With the hob CB off the RCD never trips.
Is this coincidence and it's another circuit from the CU that is faulty, or is there a fault in the hob cable that is only active when no current is flowing...?
Mysterious.
Many thanks for any help.

 

[Darkwood]

Hi Peter, Welcome to the Forum from the Staff.

 

[golfpaul]

I'd say a fault with the cable.
Have you tested it?

 

[Richard Burns]

Welcome to the forum.

Is there something else wired into the induction hob circuit, e.g cooker hood or is there a socket on the cooker isolation switch and the kettle etc. plugged into it is faulty?

 

[amlu]

loads of grease and other crap under the hob control knobs. give it an IR test and see whats up. wear gloves and clean it up if needed.

 

[davesparks]

What tests have carried out and what were the results?